Metal tube armored linear body, metal tube armoring linear body, method and apparatus for manufacturing metal tube armored linear body

ABSTRACT

An object is to provide a metallic-conduit-armored type linear member in which a linear member and the like contained in a metallic conduit do not become damaged and a defect in the metallic conduit can be repaired, a metallic conduit for armoring the linear member, and a method and a system for manufacturing the metallic-conduit-armored type linear member. 
     The method comprises a basic process (I) in which a metallic tape ( 1 ) is formed into a tubular member, a seam of the tubular member is joined to complete a sealed metallic conduit, and a metallic-conduit-armored type linear member ( 12 ) is formed by loading a linear member ( 5 ) inside the metallic conduit, and a metallic coating process (II) in which a metallic coating layer is formed on an outer surface of the sealed metallic conduit by performing plating by using a room-temperature molten-salt electrolytic bath subsequent to the basic process (I).

TECHNICAL FIELD

The present invention relates to a metallic-conduit-armored type linearmember wherein a linear member such as an optical fiber or an electricalwire, and in some cases a filler material such as a water sealingcompound in addition to the linear member, are accommodated in ametallic conduit, a metallic conduit for armoring the linear member, anda method and a system for manufacturing the metallic-conduit-armoredtype linear member. More particularly, the present invention concerns ametallic-conduit-armored type linear member in which an outer surface ofa metallic conduit is coated with metal, a metallic conduit for armoringthe linear member, and a method and a system for manufacturing themetallic-conduit-armored type linear member.

BACKGROUND ART

A linear member armored by a metallic conduit is well known as a cablewhich can be used even in a hostile environment since the metallicconduit is capable of ensuring mechanical strength and environmentalresistance. In the case of the metallic-conduit-armored type linearmember disclosed in Japanese Patent Examined Publication No. 10805/1988,an optical fiber 51, which is the linear member, is accommodated in ametallic conduit 52 as a metallic-conduit-armored type linear member 50shown in the appended FIG. 4. Such a metallic-conduit-armored typelinear member shown in FIG. 4 is used singly or as an element of acomposite cable, such as the one shown in FIG. 5, in which other cablesor tension members 54 are disposed around it. As one method ofmanufacturing such a metallic-conduit-armored type linear member, atechnique is known in which the extra length of the linear member withrespect to the length of the metallic conduit is arbitrarily adjusted topositive, zero, or negative in accordance with the working environment(e.g., Japanese Patent No. 2,505,336). Here, the extra length refers tothe difference in the length of the linear member with respect to themetallic conduit, and if the linear member is longer, the extra lengthis called positive extra length, whereas if the metallic conduit islonger, it is called negative extra length. It should be noted that theratio of the extra length to the length of the metallic conduit issometimes referred to as the extra length ratio.

A typical example of secondary processing for imparting an additionalfunction to the metallic-conduit-armored type linear member is theformation of a metallic coating layer on the surface of the armoringmetallic conduit (see a metallic coating layer 53 in FIG. 4, forexample). This metallic coating layer further improves the mechanicalstrength and environmental resistance which are the functions of themetallic conduit itself. Particularly with respect to the latter, byadopting an appropriate coating metal in the case shown in FIG. 5, forexample, it becomes possible to prevent electric corrosion due to thedifference in the ionization tendency with respect to the metalconstituting the cables or tension members 54 surrounding themetallic-conduit-armored type linear member 50. For example, JapanesePatent Unexamined Publication No. 69,716/1996 discloses a twistedassembly including tension members in which corrosion resistance isenhanced by forming a 5 to 70 μm-thick aluminum coating layer on thesurface of an armoring metallic conduit.

As a typical example of the technique for forming such a metalliccoating layer on the outer surface of a metallic conduit, theaforementioned Japanese Patent Examined Publication No. 10,805/1988 canbe cited. In this example, as shown in FIG. 6, a metallic tape 55A fedout from a tape supply 55 is formed into a tubular shape in a pipeforming step 57, in which step an optical fiber 56A is also concurrentlysupplied from a fiber supply 56, thereby forming anoptical-fiber-accommodating metallic pipe 58. Subsequently, after theseam of this pipe 58 is welded in a welding step 59, the metalliccoating layer 53 formed of, for example, aluminum is provided on theouter surface of the metallic pipe 58 by means of vacuum plating such asvacuum deposition, sputtering, ion plating, or the like in a platingstep 60. The vacuum plating is performed continuously with respect tothe metallic pipe for which welding has been completed, and the platedmetallic pipe is taken off by a takeoff 61 and is taken up by a takeup62.

In addition, in Japanese Patent Unexamined Publication No. 2,909/1985, ametallic tape is formed into a tubular shape, and an optical fiber isconcurrently supplied to form an optical-fiber-accommodated metallicpipe, and this pipe is immersed in a molten metal bath so as to weld theseam of the metallic pipe and provide a metallic coating layer on theouter surface of the metallic pipe. Further, in the aforementionedJapanese Patent Unexamined Publication No. 69,716/1996, a metallic layeris provided on the outer surface of an armoring metallic pipe in asintering process or by a chemical or electrochemical method.

However, the following problems are encountered with the conventionaltechniques. The first problem is that of the thermal effect. As alsopointed out in Japanese Patent Unexamined Publication No. 2,909/1985, ina case where the metallic coating layer is formed on the outer surfaceof the metallic conduit, the fact that the linear member in the metallicconduit receives a thermally adverse effect presents a large problem,and it does not follow that such a thermally adverse effect can beallowed in light of quality assurance just because the coating layer ofthe optical fiber is apparently not subjected to thermal damage.Particularly in the case where the linear member is a thermallysensitive substance typified by the optical fiber and in the case wherea space filler such as a water sealing compound other than the linearmember is filled in the metallic conduit, it can hardly be denied thatthe provision of vacuum plating without adopting some heating preventingmeans is very dangerous processing which directly leads to thedegradation of the quality of the metallic-conduit-armored type linearmember. Particularly in a case where it is necessary to form a thickmetallic coating layer with a thickness of not several microns orthereabouts but as much as 10 microns or more, surface treatment must begenerally effected for a relatively long time, and the possibility ofthe thermally adverse effect on the substances which are present in themetallic conduit becomes substantially high.

In addition, the thermally adverse effect during the formation of thecoating on the metallic conduit surface is also exerted on the metallicconduit itself. Namely, there is a possibility that defective weldswhich originally existed are further expanded by the thermal expansionof the metallic conduit itself and the thermal shock acting on themetallic conduit, giving rise to new defective joined portions. In thecase where a space filler material such as a water sealing compound iscontained in the sealed metallic conduit, there increases thepossibility that the thermally expanded space filler material jets outfrom such defective joined portions. Furthermore, even in a case wheresuch a space filler is not present or in a case where a thermallysensitive substance such as the optical fiber is inserted in thearmoring metallic conduit after the formation of the metallic coating,the presence or generation, per se, of the defective welds in themetallic conduit constitutes a major problem in terms of the productquality of the metallic-conduit-armored type linear member. In addition,if the plating bath infiltrates into the interior through the defectivewelds and then solidifies, there is a possibility of causing trouble tothe subsequent loading of the linear member and the space fillermaterial. The foregoing problems become no longer negligible in a casewhere a thick metallic coating layer with a thickness of as much as 10microns or more is formed on the metallic conduit or in a case where themetallic-conduit-armored type linear member is exposed under a thermaleffect for a longer period of time. To solve these problems, a perfectwelding technique is required. However, a perfect welding technique assuch does not exist.

If the conventional techniques are considered from such a perspective,in the aforementioned Japanese Patent Examined Publication No.10,805/1988 there is a teaching that the metallic pipe does not assume ahigh temperature if the metallic coating layer is formed by vacuumplating, and the coating layer of the optical fiber is therefore notsubjected to thermal damage; however, there are cases where theassertion that the plated material does not assume a high temperature byvacuum plating is contrary to the fact. In the case of theaforementioned Japanese Patent Unexamined Publication No. 69,716/1996only an enumeration is given of known film forming techniques includingsintering or chemical or electrochemical means, and there are noteachings concerning how the thermal effect, i.e., the realistic problemof product quality, is solved.

In the final analysis, the surface treatment techniques concerning themetallic conduit for armoring the linear member must have a smallthermal effect. However, that alone is insufficient in practice. It isnecessary to select an optimum surface treatment technique concernedafter taking into consideration the features of themetallic-conduit-armored type linear member and its manufacture.

Secondly, in the plating apparatus in Japanese Patent UnexaminedPublication No. 81,191/1994, in the same way as ordinary platingapparatuses for linear members (refer to, for example, Japanese PatentUnexamined Publication Nos. 132,797/1993 and 39,594/1993, JapaneseUtility Model Unexamined Publication No. 37,366/1984, Japanese PatentUnexamined Publication No. 117,243/1977, and Japanese Patent ExaminedPublication No. 23,756/1982), the traveling direction of the membersubject to treatment is changed greatly a plurality of times in theprocess of plating treatment, so that the metallic conduit containingthe optical fiber is subjected to virtual mechanical processing. Suchmechanical processing also occurs when the member to be treated which iswound around an accommodating device such as a bobbin is unwound forplating treatment or when the member is wound again around theaccommodating device after completion of plating. If such mechanicalprocessing is applied to the metallic-conduit-armored type linearmember, the metallic conduit shrinks in its longitudinal direction(refer to, for example, Japanese Patent Unexamined Publication Nos.55,804/1992 and 19,153/1993), and the extra length (positive extralength) increases more than an initial target value. Accordingly, whenthe surface of the armoring metallic conduit is provided with a metalliccoating, special consideration which takes into account such variationsin the extra length is required in product quality control.

Thirdly, if mechanical processing is repeatedly provided for themetallic conduit in the plating process, there is a possibility thatdefective welds at sealed portions are expanded or new defective weldsare produced. A similar result is also produced by the thermally adverseeffect during the formation of a coating on the metallic conduit, asdescribed above. If defective welds in the metallic conduit remain, thetechnique of continuously providing a metallic coating on the metallicconduit by the vacuum plating process disclosed in the aforementionedJapanese Patent Examined Publication No. 10,805/1988 is incapable ofpressure reduction, and therefore becomes unrealizable. Also, defectivewelding becomes an issue in a case where the metallic conduit containingthe linear member and the space filler is electrochemically formed in anelectrolyte atmosphere. Namely, the plating solution enters the interiorof the metallic conduit through defective welds, and the reaction withthe plating solution takes place inside the metallic conduit as well,causing a decline in the quality of the metallic-conduit-armored typelinear member. For this reason, even in cases where the metallic conduitsurface is electrochemically treated, special consideration is requiredwith respect to the defective welding of the metallic conduit.

The present invention has been devised in view of the above-describedaspects, and its object is to provide a metallic-conduit-armored typelinear member in which an outer surface of a metallic conduit isprovided with a metallic coating, a metallic conduit for armoring thelinear member, and a method and a system for manufacturing themetallic-conduit-armored type linear member.

DISCLOSURE OF THE INVENTION

The above object is attained by a first aspect of the inventionconcerning a linear member which is armored by a metallic conduit havinga metallic coating layer formed thereon by plating treatment which iseffected by using a room-temperature molten-salt electrolytic bath, andby a second aspect of the invention concerning a metallic conduit for ametallic-conduit-armored type linear member having a metallic coatinglayer formed thereon by plating treatment which is effected by using aroom-temperature molten-salt electrolytic bath.

In addition, the above object is also attained by a third aspect of theinvention concerning a method of manufacturing ametallic-conduit-armored type linear member having a metallic conduit onan outer surface of which a metallic coating layer is formed by platingtreatment which is effected by using a room-temperature molten-saltelectrolytic bath. In this third aspect of the invention, the metallicconduit may be formed of copper, a copper alloy, or stainless steel, andthe metallic coating layer may be formed of aluminum. In addition, theroom-temperature molten-salt electrolytic bath may be an electrolyticbath using an AlCl₃-1-butyl pyridinium chloride-based orAlCl₃-ethyl-methylimidazolium chloride-based room-temperature moltensalt. At that juncture, the electrolytic bath is preferably 80 to 150°C., more preferably 80 to 100° C.

The above object is also attained by a fourth aspect of the inventionconcerning a manufacturing method comprising: a basic step of forming asealed metallic conduit into an interior of which a linear member can beloaded, by forming a metallic tape into a tubular member and by joininga seam of the tubular member; and a metallic coating step of forming ametallic coating layer on an outer surface of the sealed metallicconduit by performing plating by using a room-temperature molten-saltelectrolytic bath subsequent to the basic step. In this fourth aspect ofthe invention, an inspecting step may be further provided between thebasic step and the metallic coating step for performing qualityinspection of the metallic-conduit-armored type linear member. Further,an extra-length adjusting step may be provided for adjusting the extralength of the linear member with respect to the sealed metallic conduit.This extra-length adjusting step need not be provided in the basic step.The extra-length adjusting step may be provided in the basic step, orthe extra length may be adjusted in a line separate from the line forcontinuously manufacturing the metallic-conduit-armored type linearmember.

In addition, the above object is also attained by a fifth aspect of theinvention concerning a manufacturing method comprising: a basic step offorming a sealed metallic conduit into an interior of which a linearmember can be loaded, by forming a metallic tape into a tubular memberand by joining a seam of the tubular member; a metallic coating step offorming a metallic coating layer on an outer surface of the sealedmetallic conduit subsequent to the basic step; and an inspecting stepprovided between the basic step and the metallic coating step forperforming quality inspection of the metallic-conduit-armored typelinear member. The metallic coating forming technique applicable in thisfifth aspect of the invention is not limited to the plating techniqueusing the room-temperature molten-salt electrolytic bath in the thirdaspect of the invention, and vacuum plating and other known film formingtechniques suffice. The basic step, the inspecting step, and theextra-length adjusting step are similar to the case of the fourth aspectof the invention.

Furthermore, the above object is also attained by a sixth aspect of theinvention concerning a manufacturing system comprising: a basicprocessing apparatus for forming a sealed metallic conduit into aninterior of which a linear member can be loaded, by forming a metallictape into a tubular member and by joining a seam of the tubular member;and a metallic coating apparatus for forming a metallic coating layer onan outer surface of the sealed metallic conduit by performing plating byusing a room-temperature molten-salt electrolytic bath. In this sixthaspect of the invention, the manufacturing system may further comprise:an inspecting apparatus for performing quality inspection of themetallic-conduit-armored type linear member fabricated by the basicprocessing apparatus, a repairing apparatus for performing necessaryrepair with respect to the metallic-conduit-armored type linear memberon the basis of the result of inspection, or an extra-length adjustingapparatus for subsequently adjusting the extra length of the linearmember with respect to the sealed metallic conduit.

As described above, in accordance with the present invention, since ametallic coating is provided on the outer surface of the armoringmetallic conduit by using the room-temperature molten-salt electrolyticbath, it is possible to provide an armoring metallic conduit providedwith a metallic coating or a linear member contained in such an armoringmetallic conduit, which is not subjected to adverse effects due to heat,moisture, and an organic solvent, and whose yield and quality as aproduct are high. In addition, in accordance with the manufacturingmethod and the manufacturing system in accordance with the presentinvention, by virtue of the metallic coating on the surface of thearmoring metallic conduit using the room-temperature molten-saltelectrolytic bath, it is possible to overcome various problems which canoccur in the subsequent metallic coating treatment owing to the presenceof defective welds and/or other causes. Furthermore, since extra-lengthcontrol is provided by estimating variations in the extra length whichoccur in the process from the fabrication of the armoring metallicconduit until completion of the metallic coating on the surface of thearmoring metallic conduit, it is possible to manufacture a high-qualitymetallic-conduit-armored type linear member whose extra length isadjusted to a target value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a basic processing apparatusof the present invention;

FIG. 2 is a schematic diagram illustrating a metallic coating apparatusof the present invention;

FIG. 3 is a schematic diagram illustrating intermediate apparatuses ofthe present invention;

FIG. 4 is a cross-sectional view of a metallic-conduit-armored opticalfiber cable;

FIG. 5 is a cross-sectional view of a composite cable using themetallic-conduit-armored optical fiber cable shown in FIG. 4;

FIG. 6 is a diagram of a conventional process for manufacturing ametallic-conduit-armored optical fiber cable; and

FIG. 7 is a diagram illustrating an example of a system formanufacturing a metallic-conduit-armored type linear member inaccordance with the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

It is essential that the technique for providing a metallic coating onthe surface of a metallic conduit for armoring a linear member has asmall thermal effect, but must be a technique which is capable offorming a metallic coating in a nonaqueous environment. If moistureremains in the metallic conduit for armoring the linear member, themetallic conduit corrodes, and the deterioration of the linear memberresults. It is known that if the linear member is an optical fiber, inparticular, the presence of the moisture leads to appreciabledeterioration of optical transmission characteristics.

However, just the requirements of the thermal effect being small and thenonaqueous system being used are still insufficient, and theaforementioned metallic coating technique must not be a technique usinga large quantity of organic solvent bath (e.g., Japanese PatentUnexamined Publication Nos. 129,989/1989 and 129,995/1989). This isbecause the large quantity of organic solvent adversely affects thesurface of the linear member and the space filler material. For example,if the surface of the linear member is resin-coated as in the case ofthe optical fiber, or is protected by a resin material as in the case ofthe electric cable, such a resin coating or resin material is dissolvedby the organic solvent. Such a phenomenon particularly constitutes aproblem if holes penetrating to both inner and outer sides remain in aweld of the metallic conduit, and it also constitutes a problem if agasified organic solvent infiltrates the interior of the metallicconduit under some circumstances. There is another problem in that thespace filler material also becomes dissolved in the organic solvent andbecomes denatured. In addition, the maintenance and management of thelarge quantity of organic solvent constitute a problem in terms ofsafety as well. Note, however, that the subject of the present inventionis not limited to a linear member which is protected by a resin coatingor a resin material.

In contrast, the electroplating technique using a room-temperature orlow-temperature molten-salt electrolytic bath (e.g., Japanese Patent No.2,540,110 and Japanese Patent Unexamined Publication No. 17,889/1989)produces a small thermal effect, it employs a nonaqueous electrolyte,and the large quantity of organic solvent is not contained in it, sothat this electroplating technique is most suitable for the metalliccoating of the metallic conduit for armoring the linear member. Thistime the inventors discovered this fact for the first time. In practice,not to mention an example in which the electroplating technique usingthe room-temperature or low-temperature molten-salt electrolytic bath isapplied to a metallic conduit containing a linear member or otherthermally sensitive substances and a space filler material, there hasbeen no former example in which a thick plating layer with a thicknessof as much as 10 μm or more is formed on the outer surface of themetallic conduit by using this technique. To be sure, there is a formerexample (e.g., Japanese Patent Unexamined Publication No. 81,191/1994)in which aluminum plating is provided at a low temperature on thesurface of a continuously traveling metal strip by using theroom-temperature or low-temperature molten-salt electrolytic bath.However, this example was devised by taking note of the fact thatplating can be effected in a low-temperature environment and the factthat the maintenance and management of the electrolyte are facilitatedsince no organic solvent bath is used, and this example was not devisedfor the specific purpose of preventing adverse effects, which areattributable to moisture and a large quantity of organic solvent, on thesubstances contained in the metallic conduit provided with a metalliccoating, and of preventing thermally adverse effects on the armoringmetallic conduit.

Thus, in the present invention, a metallic coating is provided on thearmoring metallic conduit by using the room-temperature orlow-temperature molten-salt electrolytic bath which is nonaqueous anddoes not contain a large quantity of organic solvent. Even if thethickness of the metallic coating layer exceeds 10 μm, themetallic-conduit-armored type linear member having the metallic coatingthus formed or its metallic conduit is not subjected to adverse effects,which are attributable to heat, moisture, and the organic solvent, onthe linear member typified by a thermally sensitive optical fiber and anelectric cable, a space filler material typified by a water sealingcompound, other inclusions, and the armoring metallic conduit itself,and therefore its yield and quality as a product are high.

It should be noted that the present invention does not exclude the casein which a metallic coating is provided on the surface of an armoringmetallic conduit of a metallic-conduit-armored type linear member (e.g.,Japanese Patent Examined Publication Nos. 22,921/1990 and 16,887/1992and Japanese Patent Unexamined Publication No. 108,605/1980) which isfabricated by inserting a linear member into the metallic conduit 3prepared in advance. The reason is that technical concept, per se, inwhich a metallic coating is provided on the surface of the armoringmetallic conduit by using the room-temperature or low-temperaturemolten-salt electrolytic bath is novel, and the aforementioned problemsoccurring due to the thermal effect can occur insofar as the armoringmetallic conduit is fabricated by the formation of the metal tape andthe sealing and welding of butted portions, so that such problems can beovercome by the present invention.

The metallic-conduit-armored type linear member in accordance with thepresent invention is manufactured by a method comprising: a basic stepof forming an armoring metallic conduit into an interior of which alinear member can be loaded, by joining a seam of butted portions of ametal tape formed into a tubular shape; and a metallic coating step ofproviding a metallic coating on the surface of the armoring metallicconduit. In this case, if the line for performing the basic step and theline for performing the metallic coating step are made discontinuous, itbecomes possible to effect adjustment for speed synchronization betweenan upstream step (basic step) and a downstream step (metallic coatingstep).

As for the armoring metallic conduit formed in the basic step, since theinspecting step is provided between the two steps for the thermallysensitive substance such as the optical fiber, the welded state of theseam portion of the armoring metallic conduit can be preciselyinspected, and problems which occur in a metallic coating layer on thearmoring metallic conduit can be detected prior to the metallic coating.In addition, if the inspecting step is handled in a line separate fromthe line for manufacturing the metallic-conduit-armored type linearmember in which the armoring metallic conduit is provided with ametallic coating, it becomes possible to effect adjustment for speedsynchronization between the upstream step (basic step) and thedownstream step (metallic coating step) in such a line for manufacturingthe metallic-conduit-armored type linear member.

In the present invention, a repairing step is further provided betweenthe inspecting step and the metallic coating step for repairing a defectin the metallic-conduit-armored type linear member detected as a resultof the quality inspection. For this reason, quality inspection isperformed in the inspecting step before formation of the metalliccoating layer on the outer surface of the armoring metallic conduitfabricated in the basic step so as to precisely inspect the welded stateat the seam portion of the metallic conduit, thereby making it possibleto overcome the problems which occur in the subsequent metallic coatingstep due to the presence of defective welds.

In the present invention, an extra-length adjusting step is furtherprovided for adjusting the extra length of the linear member withrespect to the sealed metallic conduit. The extra-length adjusting stepmay be provided in the basic step. Alternatively, the extra-lengthadjusting step may be performed in the same line as the line forcontinuously manufacturing the metallic-conduit-armored type linearmember, or may be performed in a line separate from the same. By virtueof such a step, control can be provided so that the extra length of thelinear member with respect to the sealed metallic conduit ultimatelyreaches a target value by taking into consideration the shrinkage of thesealed metallic conduit attributable to virtual mechanical processingwhich occurs in the process of the basic step and the metallic coatingstep and/or between the two steps. For example, in a case where thebasic step has the extra-length adjusting step, and a taking-up step fortaking up the armoring metallic conduit for which repair has beencompleted and for storing the armoring metallic conduit on a rotatingmember and a step of unwinding the armoring metallic conduit taken up inthe taking-up step so as to be used in the metallic coating step arefurther provided between the repairing step and the metallic coatingstep, there occur the shrinkage of the armoring metallic conduit, whichis attributable to virtual mechanical processing to which the armoringmetallic conduit is subjected in the taking-up and unwinding steps, andhence a change in the extra length. Therefore, a final extra lengthvalue can be set as a target value by controlling the extra length inthis extra-length adjusting step by estimating this change or furtherchanges occurring in the subsequent steps.

It should be noted that, in the above-described example, virtualmechanical processing with respect to the armoring metallic conduitoccurs due to winding around or engagement with the rotating memberrelating to the taking-up and unwinding, but also occurs due todeflection in other steps, particularly engagement with rotatingmembers. Such rotating members can be found in a large number in themetallic coating step. The reason for this is that if the deflection ofthe armoring metallic conduit is repeated, a long metallic coating routecan be secured by a small facility and a small building area.

Since the system for manufacturing a metallic-conduit-armored typelinear member in accordance with the present invention is comprised of ametallic coating apparatus for subjecting the armoring metallic conduitto plating by using a room-temperature molten-salt electrolytic bath, itis possible to manufacture a metallic-conduit-armored type linear memberwhich is high in product yield and quality by avoiding adverse effects,which are attributable to heat, moisture, and an organic solvent, on thearmoring metallic conduit itself or its inclusions. In addition, sincean inspecting apparatus is provided for performing quality inspection ofthe armoring metallic conduit fabricated by the basic processingapparatus, problems which occur in a metallic coating layer on thearmoring metallic conduit can be detected prior to the metallic coating.In this case, since a repairing apparatus is further provided, if anabnormality is detected by the inspecting apparatus, necessary repaircan be provided to obtain a sound armoring metallic conduit suitable formetallic coating treatment. In addition, since an extra-length adjustingapparatus is further provided, the extra length can be controlled sothat the extra length ultimately assumes a target value, by estimating achange in the length of the armoring metallic conduit occurring in theproduct manufacturing process or in the event that an offset in theextra length is detected by the inspecting apparatus.

Referring now to the appended FIGS. 1 to 3 and FIG. 7, a descriptionwill be given of an embodiment of the present invention. The system inthis embodiment is comprised of a basic processing apparatus I and ametallic coating apparatus II which are respectively illustrated in thedrawings.

FIG. 1 is a schematic diagram of the above-described basic processingapparatus I. As shown in the drawing, the basic processing apparatus Ifor fabricating the metallic-conduit-armored type linear member iscomprised of an assembling stage 2 including a first assembling stage 3and a second assembling stage 4 for forming a metal strip 1 into atubular shape by causing its opposite side ends to abut against eachother; an optical-fiber introducing means 6 disposed between the firstassembling stage 3 and the second assembling stage 4 so as to introduce,for example, an optical fiber cable 5 as the linear member into theformed metallic conduit; and a laser welding means 7 disposed in a stagefollowing the assembling stage 2 so as to weld the butted portions ofthe metallic conduit.

A measuring section 8 and a drawing means 9 are juxtaposed at positionsdownstream of the laser welding means 7. A traction means which includesa tension varying means 11 and a tension adjusting means 13 foradjusting the tension of a metallic-conduit-armored optical fiber cable12 is disposed between this drawing means 9 and a cable takeup 10.

An extra-length controlling means for adjusting the relative length,i.e., extra length, of the optical fiber cable with respect to themetallic conduit is formed by the tension varying means 11, the tensionadjusting means 13, a tension adjusting means 14 disposed in a stagepreceding the assembling stage 2 so as to adjust the tension of themetal strip 1, and a tension adjusting means 15 for adjusting thetension of the optical fiber cable 5. The extra-length controlling meansmakes it possible to set the extra length to a positive extra length, azero extra length, or a negative extra length by adjusting the tension,and its value can be set to a desired value.

The metallic-conduit-armored optical fiber cable 12 is temporarily takenup onto a bobbin by the aforementioned cable takeup 10 at a terminatingend of the basic processing apparatus I, and is subsequently supplied tothe metallic coating apparatus II, which will be described later, toprovide a metallic coating.

As a specific example of the metallic-conduit-armored type linearmember, it is possible to cite the following, by way of example.

Size of the metallic conduit: In the case of SUS 304

inside diameter/outside diameter (φ mm)=1.8/2.2 to 3.2/3.6

wall thickness: 0.2 mm

Optical fiber: 250 μm, a maximum of 24 fibers can be inserted in theaforementioned metallic conduit

Overall length (km): 5 km or more

Filler material: synthetic oil (heat resistance: 100° C. or less)

In addition, in its modifications, the linear member may be a pluralityof optical fibers with tension members disposed therearound, a single ora plurality of optical fibers coated with ultraviolet-curing acrylateresin (heat resistance: 80° C. or thereabouts), an electric cable, orother linear members, while the armoring metallic conduit may be made ofmetal including copper, a copper alloy, and an iron-based alloy.

The armoring metallic conduit not containing the linear member isfabricated by the basic processing apparatus I shown in FIG. 1. Namely,it suffices if the metal strip 1 is formed by the assembling stage 2without supplying the linear member 5 and is formed into a tubular shapeby causing opposite side ends to abut against each other, buttedportions are sealed by the laser welding means 7 which welds them, andthe armoring metallic conduit thus formed is taken up onto the bobbin 10via the drawing means 9. This armoring metallic conduit not containingthe linear member is supplied to the metallic coating apparatus II,which will be described later, to provide a metallic coating. Further,the linear member is inserted into its interior by using the techniqueshown in Japanese Patent Examined Publication No. 22,921/1990 or16,887/1992, Japanese Patent Unexamined Publication No. 108,605/1980, orthe like, contributing to the manufacture of themetallic-conduit-armored type linear member. In this context, that whichis fabricated by the basic processing apparatus I will be generallyreferred to as the “armoring metallic conduit,” unless otherwisespecified, regardless of whether or not the linear member is loaded inits interior.

Next, referring to FIG. 2, a description will be given of the metalliccoating apparatus II in which the armoring metallic conduit (whether ornot the linear member or the space filler material are provided in itsinterior is disregarded; hereinafter the same) fabricated by theabove-described basic processing apparatus I is treated.

The metallic coating apparatus II has in the front and in the rear of abath 21 an opening portion 23 for leading the armoring metallic conduit12 into it and an opening portion 24 for leading the armoring metallicconduit 12 out of it, respectively, and seal rolls 25 are respectivelyfitted in these opening portions 23 and 24, the bath 21 being thussealed in a semihermetic state. A plurality of energizing rolls 28 and aplurality of sink rolls 29 are arranged in an upper portion and on thebottom side inside the bath 21, respectively, the armoring metallicconduit 12 is wound around these rolls alternately, and the armoringmetallic conduit 12 introduced from the opening portion 23 repeatedlymoves in upward and downward directions and is led to the outside fromthe opening portion 24.

The supply of the armoring metallic conduit 12 to the metallic coatingapparatus II is effected by the feeding of the armoring metallic conduit12 from a storing bobbin by a feeder 20. After known pretreatment isprovided for the armoring metallic conduit 12, the armoring metallicconduit 12 is introduced into the apparatus II. After passing throughthe apparatus, the armoring metallic conduit 12 is fed to the outside,is subjected to appropriate post-treatment, and is accommodated again bybeing wound around a bobbin by a takeup 32. The movement of such anarmoring metallic conduit 12 is effected by traction by the takeup 32 orby traction by the driving of the respective energizing rolls 28.

In the apparatus II, an inert-gas supplying pipe 26 is provided on anupper surface of the bath 21 to supply an inert gas whose dew point isadjusted to −10° C. or less, so that the internal pressure is maintainedat a level higher than the atmospheric pressure by 0.05 mm or more. Theinert gas before being supplied is cooled by a cooler 27 disposed midwayin the inert-gas supplying pipe 26, and its dew point is adjusted to−10° C. or less.

Then, at portions opposing the armoring metallic conduit 12 which movesvertically between the energizing rolls 28 and the sink rolls 29, anodeplates 30 are arranged in parallel on both sides of the armoringmetallic conduit 12. Nozzles 31 are each disposed in an upper portionbetween the anode plate 30 and the armoring metallic conduit 12 to ejecta plating electrolyte therebetween.

As this electrolyte, an AlCl₃-1-butyl pyridinium chloride-based orAlCl₃-ethyl-methylimidazolium chloridebased room-temperature molten saltis ejected from each nozzle 31. The former is composed of 67 mol % AlCl₃and 33 mol % butyl pyridinium chloride as disclosed in, for example,Japanese Patent No. 2,540,110. According to such a nonaqueouselectrolyte which does not employ an organic solvent, aluminumelectroplating is possible at high speed at 100° C. or less, and sinceelectroplating is possible at 80 to 150° C. which is sufficiently lowerthan the conventional process, the plating temperature can beappropriately set within this range in accordance with the properties ofthe armoring metallic conduit 12 subject to plating, i.e., in accordancewith the presence or absence of the linear member, the kind andcharacteristics of the contained linear member, and the like. For thisreason, the thermally adverse effect on the butt-connected portion ofthe armoring metallic conduit 12 can be avoided, and the surface of thearmoring metallic conduit can be coated with metal without adverselyaffecting the thermally sensitive linear member and space fillermaterial whose degradation in their characteristics and degeneration canbe otherwise caused by the organic solvent or moisture which can bepresent in its interior.

The thickness of the aluminum coating thus formed can be set to 10 μm ormore, e.g., 12 to 18 μm. In addition, the temperature of theelectrolyte, i.e., the plating temperature, can be set in accordancewith the heat-resisting temperature of the resin for coating the opticalfiber core. The traveling speed of the armoring metallic conduit beingplated is set by taking into consideration the viscosity of theelectrolyte, its electrical conductivity (current velocity), platingthickness, the denseness of the plating layer, the number of platingbaths, and the like, but the traveling speed of the armoring metallicconduit is generally set to 5 m/min or more.

In accordance with the embodiment shown in FIGS. 1 and 2, after themetallic-conduit-armored type linear member is temporarily taken up ontothe bobbin by the cable takeup 10 at the terminating end of the basicprocessing apparatus I, the metallic-conduit-armored type linear memberis supplied to the metallic coating apparatus II where the outer surfaceof the armoring metallic conduit is provided with a metallic coating.However, the present invention is not limited to the same, and ametallic coating layer may be continuously formed on the surface of themetallic conduit for the metallic-conduit-armored type optical fiberwhose extra length has been controlled, by a series of longitudinal-lineprocessing of the basic process and the metallic coating process basedon a series connection of the basic processing apparatus I and themetallic coating apparatus II as shown in FIG. 7. It should be notedthat, in either case, washing, pickling, cleaning, drying, surfacetreatment (e.g., nickel plating treatment) for improving the adhesion ofthe coating metal on the metallic conduit surface, and otherpretreatment are provided in advance for the outer surface of themetallic conduit immediately before being supplied to the metalliccoating apparatus II, regardless of whether or not the linear member isalready contained in its interior.

The fabrication of the armoring metallic conduit and metallic coatingtreatment based on the discontinuous arrangement of the basic processingapparatus I and the metallic coating apparatus II shown in FIGS. 1 and 2on the one hand, and processing based on the continuous arrangement in asingle longitudinal line of the basic processing apparatus I and themetallic coating apparatus II shown in FIG. 7, i.e., processing in whichthe armoring metallic conduit fabricated by the apparatus I is directlyfed to the apparatus II, on the other hand, are common in that both areexamples of the embodiment in accordance with the present invention.However, the former processing differs from the latter processing inthat the armoring metallic conduit can be temporarily stored on thebobbin 10, and the apparatus I and the apparatus II can be cut off fromeach other. For this reason, in a case where a difference is notedbetween the traveling speed of the armoring metallic conduit in theapparatus I and that in the apparatus II, the running of one apparatusinterferes with the running of the other in the latter processing, andthe adjustment of interlocking conditions or speed synchronizationbetween the two apparatuses is relatively difficult, so that specialconsideration is required. In the former processing, however, since thearmoring metallic conduit can be temporarily stored on the bobbin 10,and the apparatus I and the apparatus II can be cut off from each other,the adjustment of speed synchronization between the two apparatuses isfacilitated, so that this arrangement is more preferable.

Next, a description will be given of another embodiment of the presentinvention. In the foregoing embodiment, the armoring metallic conduitformed by the basic processing apparatus I is brought to the metalliccoating apparatus II to form a metallic coating on its outer surface.This embodiment, however, is characterized in that an inspectingapparatus, or a repairing apparatus together with the same, is disposedas an intermediate apparatus or apparatuses. Although the inspectingapparatus is also present in the measuring section 8 of the apparatus I,it is preferred that the inspecting apparatus used in the inspectingprocess effected between the basic processing process and the metalliccoating process be of higher accuracy than the measuring section 8, or adifferent kind of a measuring technique be applied. If the apparatus Idoes not have the measuring section 8, this inspecting process mayreplace the same.

The intermediate apparatus III in this embodiment may be formed as partof the continuous line in which the armoring metallic conduit 12 iscontinuously made to travel between the basic processing apparatus I andthe metallic coating apparatus II, or may be formed as a separate lineby removing from the line the armoring metallic conduit 12 wound aroundthe bobbin. However, in view of the fact that the apparatus I and theapparatus II are discontinuous, the latter arrangement is preferablesince the adjustment of speed synchronization between the twoapparatuses is facilitated.

In a preferred form of the present invention, the intermediate apparatusIII has together with an inspecting apparatus 41 a repairing apparatus42 as well, but only the former may be provided, or an inspectingapparatus having a repairing function (e.g., refer to Japanese UtilityModel Unexamined Publication No. 92,485/1986) may be used. Theinspecting apparatus 41 detects flaws in the metallic conduit by meansof, for instance, a magnetic or optical means, and the repairing means42 repairs the metallic conduit by rewelding defective portions by, forinstance, laser irradiation.

The intermediate apparatus III shown in FIG. 3 also has the repairingapparatus 42 together with the inspecting apparatus 41 as a preferredform of the present invention. According to this embodiment, before ametallic coating layer is formed on the outer surface of themetallic-conduit-armored type linear member, fabricated by the basicprocessing apparatus I, by the metallic coating apparatus II, themetallic-conduit-armored type linear member is taken up onto the bobbinand is temporarily removed from the manufacturing line, and processingin a separate line is provided. Namely, quality inspection is firstperformed by the inspecting apparatus 41. As a result, the welded stateof the seam of the armoring metallic conduit is precisely inspected, andif the result is satisfactory, the armoring metallic conduit is woundaround the storing bobbin in accordance with a loop 43, and issubsequently subjected to metallic coating treatment in the originalmanufacturing line. If the result of inspection is unsatisfactory andthe armoring metallic conduit cannot be repaired, the armoring metallicconduit is rejected from the loop 43, i.e., discarded or used for adifferent application, and is not subjected to the subsequent metalliccoating treatment in the original manufacturing line. However, if thearmoring metallic conduit is repairable, the armoring metallic conduitis sent to the repairing apparatus 42 in the loop 43, and after it isrepaired, the armoring metallic conduit is subjected to metallic coatingtreatment in the original manufacturing line.

If the armoring metallic conduit is repaired in the above-describedmanner, the metallic-conduit-armored type linear member which canwithstand the subsequent metallic coating process can be regenerated,and the virtual product yield can be improved. Such a regenerationmeasure is important particularly in the case of long products.

Specifically, in the process of immersing the armoring metallic conduitin the plating bath as in the present invention, the following problems,among others, constitute intrinsic problems: the problem that the innerwall of the metallic conduit becomes plated and the filler material jetsout from defective welds to the outside due to heat; the problem thatwelding defects become enlarged due to deformation accompanying a changein the traveling direction in the plating process, making it impossibleto effect processing in that process or its subsequent processes; andthe problem that particularly in the case where the linear member isafterwards inserted into the armoring metallic conduit, if theelectrolyte infiltrates into the interior from the defective welds andsolidifies, trouble is caused to the insertion itself. In accordancewith this embodiment, however, since inspection and repair are performedwith respect to the armoring metallic conduit before being subjected tometallic coating treatment, the number of defective welds present priorto metallic coating treatment and the probability of occurrence ofdefective welding during the relevant treatment can be minimized, sothat the aforementioned intrinsic problems can be overcome.

Further, in a case where a plurality of taking-up processes andunwinding processes are provided between the basic process and themetallic coating process, since the extra-length adjusting process isprovided in the basic process, a final extra length value can be set asa target value by controlling the extra length in the upstream processby estimating the shrinkage of the metallic conduit, which isattributable to mechanical processing to which the metallic conduit issubjected in the taking-up and unwinding processes, and hence a changein the extra length.

It is not necessary for the extra-length adjusting process to bepositioned in the basic process. Although the extra-length adjustingprocess may be provided in the basic process, the adjustment of extralength may be made in a process separate from the basic process and themetallic coating process or by an apparatus separate from the basicprocessing apparatus I and the metallic coating apparatus II. Inparticular, the latter case in which the adjustment is made in aseparate process or by a separate apparatus is effective in a case whereexcessive negative extra length resulted in the extra-length adjustmentin the former case. As examples of the former case, it is possible tocite an extra-length adjusting means provided in the apparatus I itselfand a specially added in-line extra-length adjusting means (JapanesePatent Unexamined Publication No. 19,153/1993). This is suitable for amanufacturing line in which the apparatuses I and II are arranged in aseries as shown in FIG. 7 to continuously manufacture and process thearmoring metallic conduit, as well as for its manufacturing process. Asan example of the latter case, it is possible to cite Japanese PatentUnexamined Publication No. 55,804/1992. If extra-length adjustment is tobe made in the intermediate apparatus III shown in FIG. 3, it ispreferable to install the extra-length adjusting means at position A.The reason is that it suffices if the extra-length adjustment isprovided only with respect to nondefective products which passed theinspecting process and the repair process.

By virtue of such an extra-length adjustment process, control can beprovided so that the extra length of the linear member with respect tothe metallic conduit ultimately reaches a target value by taking intoconsideration the shrinkage of the metallic conduit due to virtualmechanical processing (repetition of 180° change in the travelingdirection by the rolls in the metallic coating apparatus in FIG. 2, forinstance) which occurs between the basic process and the metalliccoating process and/or in the metallic coating process.

The above description is given as a mere enumeration of embodiments forspecifically realizing the present invention, and the present inventionis therefore not limited to the foregoing embodiments.

Claims:
 1. A method of manufacturing a metallic-conduit-armored typelinear member which is armored by a metallic conduit, comprising thesteps of forming a plating layer on a surface of said metallic conduitand forming a metallic coating layer on said plating layer by platingtreatment which is effected by using a room-temperature molten-saltelectrolytic bath.
 2. The method of manufacturing ametallic-conduit-armored type linear member according to claim 1,wherein a metallic tape is formed of copper, a copper alloy, orstainless steel, and said metallic coating layer is formed of aluminum.3. The method of manufacturing a metallic-conduit-armored type linearmember according to claim 1, wherein said room-temperature molten-saltelectrolytic bath is an electrolytic bath using an AlCl₃-1-butylpyridinium chloride-based or AlCl₃-ethyl-methylimidazoliumchloride-based room-temperature molten salt.
 4. The method ofmanufacturing a metallic-conduit-armored type linear member according toclaim 1, wherein said electrolytic bath is 80 to 150° C.
 5. The methodof manufacturing a metallic-conduit-armored type linear member accordingto claim 1, wherein said electrolytic bath is 80 to 100° C.
 6. A methodof manufacturing a metallic-conduit-armored type linear member,comprising: a basic step of forming an armoring metallic conduit into aninterior of which a linear member can be loaded, by forming a metallictape into a tubular member and by joining a seam of said tubular member;a plating step of forming a plating layer on the surface of saidmetallic conduit; and a metallic coating step of forming a metalliccoating layer on said plating layer by performing plating by using aroom-temperature molten-salt electrolytic bath.
 7. The method ofmanufacturing a metallic-conduit-armored type linear member according toclaim 6, further comprising: an inspecting step provided between saidbasic step and said plating step for performing quality inspection ofsaid armoring metallic conduit.
 8. The method of manufacturing ametallic-conduit-armored type linear member according to claim 7,further comprising: a repairing step provided between said inspectionstep and said plating step for repairing a defect in said armoringmetallic conduit as a result of said quality inspection.
 9. The methodof manufacturing a metallic-conduit-armored type linear member accordingto claim 6, further comprising: an extra-length adjusting step foradjusting the extra length of said linear member with respect to saidarmoring metallic conduit.
 10. The method of manufacturing ametallic-conduit-armored type linear member according to claim 9,wherein said extra-length adjusting step has a step of providing controlsuch that the extra length of said linear member with respect to saidarmoring metallic conduit ultimately reaches a target value, by takinginto consideration a longitudinal shrinkage of said armoring metallicconduit due to virtual mechanical processing occurring between saidbasic step and said metallic coating step or in said metallic coatingstep.
 11. The method of manufacturing a metallic-conduit-armored typelinear member according to claim 10, wherein said virtual mechanicalprocessing is processing which occurs as a result of engagement of saidarmoring metallic conduit with a rotating member.
 12. A method ofmanufacturing a metallic-conduit-armored type linear member, comprising:a basic step of forming an armoring metallic conduit into an interior ofwhich a linear member can be loaded, by forming a metallic tape into atubular member and by joining a seam of said tubular member; aninspecting step for performing quality inspection of said armoringmetallic conduit; a plating step of forming a plating layer on thesurface of said metallic conduit; and a metallic coating step of forminga metallic coating layer on said plating layer by performing plating byusing a room-temperature molten-salt electrolytic bath.
 13. The methodof manufacturing a metallic-conduit-armored type linear member accordingclaim to 12, further comprising a repairing step provided between saidinspection step and said plating step for repairing a defect in saidarmoring metallic conduit detected as a result of said qualityinspection.
 14. The method of manufacturing a metallic-conduit-armoredtype linear member according to claim 12, wherein said basic step has anextra-length adjusting step for adjusting the extra length of saidlinear member with respect to said armored metallic conduit, and ataking-up step for taking up said armoring metallic conduit for whichrepair has been completed and for storing said armored metallic conduiton a rotating member and a step of unwinding said armoring metallicconduit taken up in said taking-up step so as to be used in saidmetallic coating step are further provided between said repairing stepand said plating step.
 15. The method of manufacturing ametallic-conduit-armored type linear member according to claim 12,further comprising: an extra-length adjusting step for adjusting theextra length of said linear member with respect to said armoringmetallic conduit.
 16. The method of manufacturing ametallic-conduit-armored type linear member according to claim 15,wherein said extra-length adjusting step has a step of providing controlsuch that the extra length of said linear member with respect to saidarmoring metallic conduit ultimately reaches a target value, by takinginto consideration a longitudinal shrinkage of said armoring metallicconduit due to virtual mechanical processing occurring between saidbasic step and said metallic coating step or in said metallic coatingstep.
 17. The method of manufacturing a metallic-conduit-armored typelinear member according to claim 16, wherein said virtual mechanicalprocessing is processing which occurs as a result of engagement of saidarmoring metallic conduit with a rotating member.
 18. A system formanufacturing a metallic-conduit-armored type linear member, comprising:a basic processing apparatus for forming an armoring metallic conduitinto an interior of which a linear member can be loaded, by forming ametallic tape into a tubular member and by joining a seam of saidtubular member; a plating apparatus for forming a plating layer on asurface of said armoring metallic conduit; and a metallic coatingapparatus for forming a metallic coating layer on said plating layer byperforming plating by using a room-temperature molten-salt electrolyticbath.
 19. The system for manufacturing a metallic-conduit-armored typelinear member according to claim 18, further comprising: an inspectingapparatus for performing quality inspection of said armoring metallicconduit fabricated by said basic processing apparatus.
 20. The systemfor manufacturing a metallic-conduit-armored type linear memberaccording to claim 19, further comprising: a repairing apparatus forrepairing flaws in said armoring metallic conduit detected by saidinspecting apparatus.
 21. The system for manufacturing ametallic-conduit-armored type linear member according to claim 18 or 19,further comprising: an extra-length adjusting apparatus for adjustingthe extra length of said linear member with respect to said armoringmetallic conduit.
 22. A metal-conduit-armored linear member assembly,comprising: a linear member; a metallic conduit body for armoring saidlinear member; an aluminum coating layer provided on said metallicconduit body; and a nickel plating layer provided between said metallicconduit body and said aluminum coating layer to improve adhesion betweensaid metallic conduit body and said aluminum coating layer.
 23. Ametal-conduit-armored linear member assembly according to claim 22,wherein said linear member is an optical fiber.
 24. Ametal-conduit-armored linear member assembly according to claim 22,wherein said metallic conduit body further armors a water sealingcompound.
 25. A metallic conduit for armoring an optical fiber, saidmetal conduit comprising: a metallic conduit body; an aluminum coatinglayer provided on said metallic conduit body; and a nickel plating layerprovided between said metallic conduit body and said aluminum coatinglayer to improve adhesion between said metallic conduit body and saidaluminum coating layer.
 26. A metallic conduit according to claim 25,which further armors a water sealing compound.